package com.example.socket.server.nio;

import org.checkerframework.checker.units.qual.A;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.nio.ByteBuffer;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

/**
 * @author xurongbei
 * 缺点：假如10000个连接中只有1000个有事件的连接，那么每次都遍历10000个连接，就会造成资源的浪费
 */
public class NioSocketServer {

    /**
     * 保存客户端连接
     */
    static List<SocketChannel> channelList = new ArrayList<>();

    public static void main(String[] args) throws IOException {
        //创建NIO ServerSocketChannel，与BIO的serverSocket类似
        ServerSocketChannel serverSocket = ServerSocketChannel.open();
        serverSocket.socket().bind(new InetSocketAddress(9000));
        //设置ServerSocketChannel为非阻塞
        serverSocket.configureBlocking(false);
        System.out.println("服务启动成功");
        while (true){
            //非阻塞模式accept方法不会阻塞，否则会阻塞
            //NIO 的非阻塞是由操作系统内部实现的，底层调用了linux内核的accept函数
            SocketChannel socketChannel = serverSocket.accept();
            //如果有客户端进行连接
            if(socketChannel!=null){
                System.out.println("连接成功");
                //设置SocketChannel为非阻塞
                socketChannel.configureBlocking(false);
                //保存客户端连接在List种
                channelList.add(socketChannel);
            }
            //遍历连接进行数据读取
            Iterator<SocketChannel> iterator = channelList.iterator();
            while (iterator.hasNext()){
                SocketChannel sc = iterator.next();
                ByteBuffer byteBuffer = ByteBuffer.allocate(16);
                //非阻塞模式read方法不会阻塞，否则会阻塞
                int len = sc.read(byteBuffer);
                //如果有数据，把数据打印出来
                if(len>0){
                    System.out.println("接收到消息："+new String(byteBuffer.array(),0,len,"GBK")+"   :   "+sc.getRemoteAddress().toString());
                    //如果客户端断开，把socket从集合种去掉
                }else if(len == -1){
                    iterator.remove();
                    System.out.println("客户端断开连接");
                }
            }
        }
    }
}
